Refrigeration system with multiple impellers and shell evaporators



N. H. GAY

Dec. 19, 1933.

Filed Jan. 15, 1932 3 Sheets-Sheet l UB5; mum:

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REFRIGERATIQN SYSTEM WITH MULTIPLE IMPELLERS AND SHELL EVAPORATORS FiledJan. 15, 1932 3 Sheets-Sheet 2 I f V Ni HAEL gHmlllllllllllllllllilllllfi iimll lll N. H. GAY

Dec. 19, 1933.

REFRIGERATION SYSTEM WITH MULTIPLE IMPELLERS AND SHELL EVAPORATORS FiledJan. 15, 1932 3 Sheets-Sheet 3 gmnntog,

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Patented Dec. 19, 1933 REFRIGERATION SYSTEM WITH MULTIPLE IMPELLERS ANDSHELL EVAPORATORS Norman H. Gay,

Application January 15,

9 Claims.

This invention relates to improvements in heat transfer means forrefrigerating systems, and is illustrated as applied to the brine tankand ice field portion of an ice manufacturing plant.

One of the features of the present invention is the provision of animpeller system for causing brine or other refrigerant mediums tocirculate in maximum volume through an evaporator and in still greatervolume through that portion of the system where it is desired to causefreezing or congealing of the product.

Another feature of the present invention is the provision of arefrigerating structure with associated parts whereby a high velocity ofbrine or otherliquid flow through the ice field or like structure may beaccomplished with a given size of evaporator. 7

Another feature of the present invention is the provision of a tubularevaporator having a special arrangement of tubes not heretofore used inrefrigerating structures, which said arrangement of tubes permits alarge amount of space for separation of liquid and gaseous refrigerantbefore said gaseous refrigerant leaves said evaporator.

Another feature of the invention is the provision of means for movingthe brine at a high rate of speed in cycle.

Further features of the invention concerning details of construction ofi the several parts, will appear in thecourse of the followingspecification and claims. 1

An illustrative form of practicing the invention is shown on theaccompanying drawings, in which Figure 1 is a horizontal diagrammaticalplan, with parts in section, showingthe relationship of the evaporator,brine impelling'system and ice field to one another.

Figure 2 is a vertical sectional view substantially on line 22 of Figure1.

Figure 3 is a vertical detail view on a larger scale, .partly insection, of the hood end of the evaporator. I V

Figure 4 is a vertical sectional view through the evaporator shell on alarger scale.

Figure 5 is a detail sectional view on line 5 of Figure 4.

Figure dis a sectional view, on a larger scale, of the brine impellingstructure.

Figure 7 is a sectional view on line '7-'7 of Figure 6, of the shaftstabilizing members.

Figure 8 is a sectional View, on line 8-8 of Figure 6. i i

In the drawings, the evaporator structure is shown employed with an icefield which is surrounded by tank walls 10 of heat insulating ma LosAngeles, Calif.

1932. Serial No. 586,928

terial. An offset 11 of these walls provides a space for the motor fordriving the brine impeller. Within the tank are the longitudinalpartitions 12 which extend from top to bottom of the tank to cause acirculation of the brine as will be described hereinafter, and for thispurpose terminate short of the end Walls 10. Within the tank are showncans 13 of usual type, which may be arranged and supported in any usualway. Opposite the offset portion 11, a clear space is provided withinwhich the evaporator may be located. Within this space the angularlydirected walls 12 extend from partitions 12a toward the offset walls 11(Figure l) and then are closed by an end wall 121), so that the walls12, 12a, and 12b extend continuously, and permit passage of brine fromone side thereof to the other only at their ends and through a hood inwall 12b as will be described hereinafter.

It will be'understood that the illustrative form sets out what may betermed a twin type of ice field and evaporator circulating system, sincethe two ice fields are fed by branched circulating currents of brine;and that the operation is the same if one ice field is shut off or if itbe eliminated entirely.

The evaporator comprises the shell 15 having a conical extension 16terminating in a shell hood 17. The conical extension 16 has a splitmarginal flange 18 which may be clamped upon the end of the shell 15 bythe bolt 19 (Figs. 2 and 3).

The evaporator, besidesthe jacket shell 15, in cludes a pair of end orheader plates 20, 21, which are preferably secured in the shell by awelded seam 22, (Figure 5). These header plates are provided withaligned holes through which pass the brine tubes 24, which preferablyare secured in the headers by rolling, or in another manner whichprovides a security against longitudinal movement and a proper packingof the joints. Leading to the bottom of the chamber formed by the shelland its headers is an inlet pipe 30 for liquid refrigerant, while alarger off-comer pipe 31 provides for the withdrawal of vaporizedrefrigerant, from the shell chamber. It will be noted that the tubes 24do not fill the shell, but leave free a space equal to about one-quarterof the cross sectional area of the shell. It will be understcod that inoperation the shell is filled with liquid refrigerant ,to a level asindicated in Figure '4, so that a considerable free space is left inwhich gaseous refrigerant'may separate from liquid refrigerant, prior towithdrawal from the shell.

The impeller system comprises a shaft 40 lo- 110 cated in bell 41 havinga flange 42 secured to the offset wall 11 (Figure 6), so that the bellitself extends through this wall and is sealed with respect thereto. Ateach end of the bell is provided a bearing 43, 44 for the shaft. At theinner end of the bell are arranged the strut or stiffener rods 45 whichextend radially away from the shaft and are secured to brace members 46joined to the hood 48 which is secured to the wall 12b. Within the hood48, the shaft 40 carries an impeller fan or propeller blade 50 havingits hub 51 keyed and secured to the shaft. Beyond the impeller blading50, the shaft is provided with a spacer sleeve 52 at the end of which isprovided a second impeller blading 53 which likewise has its hub 54keyed to the shaft 40. A locking cap 55 of streamline form is preferablyscrewed to the end of the shaft and held against rotational movementrelative to the shaft by a screw 56 passed into the hub 5%.

At the end of the shaft l0, projecting from the outer end of the bell 41is keyed and secured a pulley 5'7 which is driven by any suitable motivepower.

Within the bell is provided a partition wall 58 which carries thepacking 59 around the shaft 40, which may be clamped into sealingcondition by a gland 60.

In operation, liquid refrigerant is delivered through the pipe 30 andgaseous refrigerant is drawnofif through the off-corner pipe 31 to acompressor for recompression, condensation and re-- turn in cycle. Anydesired type of compressorcondenser system may be employed, and owing tothe well-known structures of such plants, they have not beenillustrated. 1

The pulley 5'7 is then set in rotation with its shaft 40 so that theimpeller bladings 50, 53 are driven and cause a movement, of the brineor other liquid (hereinafter referred to as brine from the space at oneside of the partition 12 (above, Figure 1) to the other side of thepartition (below, Figure 1). The impeller 50 will, due to the greaterresistance of the tubes to pa sage of brine (or if desirable, may bedesigned to), deliver a greater volume of brine through the partition1212 than is forwarded by the blading 53 through the shell 15. Hencethere is a, constant escape of brine from between the heads 48 and 17into the space surrounding the shell 15 (Figure 1), and thus ahigherhead of pressure may be built up at the two sides of the walls12a, 12b, than if all the brine were forced through the tubes. Forexample, heads of 6 to 8 inches and more may thus be developed. Theimpeller 53, however, continuously operates to force the largestconsistent quantity of the brine through the evaporator tubes.

Owing to the friction created within the tubes of the evaporator shell,only a definite quantity of brine may be driven therethrough at a givenpressure. The impeller blading 53 causes an increase in this pressurereceiving the brine at the pressure head given it by the blading 50 andby this increase in pressure accelerating the movement of the brinethrough the tubes. While within the tubes, a very rapid and energeticcooling of the brine occurs so that it is ultimately delivered at theother end of the shell (bottom of Figure 1) in a colder condition. Itmingles with the brine which has escaped between the hoods 48 and 17 andbecause of the increase in volume due to the addition of this escapedbrine, and the head created'and maintained by impeller 50, circulatesrapidly past the cans to the end of partition 12, in either direction,and then returns back to the hood 48 for repumping by the blading 50.The very rapid circulation thus eiiected causes a quick chilling of thematerials in the cans. It will be noted that even the exterior of theshell is thus employed for cooling brine, and that this cooling effectis produced on brine which has the same temperature as the brineentering the tubes.

It will be understood that this propeller type of blading has acharacteristic like that of the centrifugal pump in that as theresistance to flow builds up the circulated volume drops. Hence, for anygiven speed of the impeller 53, no matter how much care is taken forenclosing the flow between the impeller 53 and the shell, the volumewill not be increased owing to the relatively fixed friction losses atgiven volumes, of brine traveling within the brine tubes.

It may be pointed out that with the impellers 20 inches in diameter,about 1100 cubic feet of brine may be handled per minute, and with 30inch impellers, about 1680 feet per minute at normal operating speeds.400 cubic feet may be passed through a 150 tube evaporator of standardconstruction and 750 feet through a 250 tube evaporator. By providingthe two impellers and an escape opening between the Of this volume,about impellers, the first impeller operates to deliver its fullquantity of brine at its normal pressure head whereby to cause theregular flow of brine in the can portion of the circuit. The secondimpeller 53 operates to increase the relative pressure head on the brinepassing through the tubes over and above the head or level within thespace surrounding the evaporator and thus cause the greatest flow ofbrine possible through the tubes.

By providing the offset 11 in the walls of the ice tank it is possibleto house the ice tank in a rectangular building, without interferencewith the space afforded the ice cans in the ice field proper, and at thesame time to have the impeller motor'located within the building.Further, this arrangement in conjunction with the walls 12a, 12b permitsthe use of a relatively short drive shaft and a close connection betweenthe motor and the shaft, whereby space is saved. The motor M issupported on a shelf carried by a bracket secured to the verticaloilset' wall 11 of the brine tank, and preferably a strut connection 101is provided between the outer edge of this shelf and the housing 41(Figure'Z).

It will be understood that a particular feature of the invention is theprovision of the multiple impellers, one serving to effect a generalcirculation of brine, and the other to move a part of the brine throughthe evaporator structure; together with means for operating the impellerand that the invention is not limited in these respects to theillustratedform in which a common driving means and coaxial impellersare provided.

Further, it will be understood that the structure is applicable for thecooling and circulation of any heat exchange medium, which must beunderstood as included broadly under the term brine as used herein; andthat the heat exchange medium may be employed for various purposes atthe points described herein as an ice field. The illustrative employmentof brine and an ice field as means of practicing the invention isintended as a specific example only, since the invention may obviouslybe employed and this example changed in many ways without departing fromthe scope of the appended claims.

Having thus described the invention, what I claim as new and desire tosecure by Letters Patent is:

1. In a refrigeration system operating with a circulating heat-exchangemedium, a heatyielding element, a heat-absorbing element, first impellermeans for establishing a circulation of the medium over saidheat-yielding element, second impeller means for passing a part of thecirculating medium over said heat-absorbing element, and a by-pass forthe remaining part of the circulating medium around the heat-absorbingelement.

2. A refrigeration system comprising a brine tank, a partition in saidtank to control the direction of flow therein, an evaporator located insaid tank at one side of said partition, and two impellers, one of saidimpellers being arranged to move the brine from one side of saidpartition to the other whereby to establish a circulation of the brine,and the other impeller being arranged to force a portion or" thecirculated brine into contact with said evaporator, the remainingportion of the circulated brine being permitted to bypass theevaporator.

3. A. refrigeration system comprising a brine tank, a partition in saidbrine tank to control the direction of flow therein and having an oilset to provide wider and narrower compartments, an evaporator located insaid wider compartment, a first impelling means located in the offsetportion of said partition for moving the brine from one side of saidpartition to the other whereby to establish a brine circulation, asecond impelling means to force a portion of said circulating brine oversurfaces of the evaporator, the remaining portion of the circulatedbrine being permitted to bypass said evaporator.

4. A refrigerating system comprising a brine tank, a partition in saidtank to control the direction of flow therein and having an offsetwhereby to provide a wider and a narrower compartment adjacent oneanother and separated by said oiTset of the partition, a shell-and-tubeevaporator located in said wider compartment, a first impelling meansfor forcing brine from said narrower compartment into said widercompartment whereby to establish a circulation of brine, and a secondimpelling means for forcing brine through said evaporator.

.5. A refrigerating system comprising a brine tank having an offset inone wall thereofi a partition in said tank to control the direction offlow therein and having an offset in alignment with said wall whereby toprovide a narrower compartment between said offsets and a widercompartment adjacent said narrower compartment, an evaporator located insaid wider compartment, a shaft extending through. saidofisets, twoimpellingmeans on shaft, one of said impelling means serving to movebrine from said narrower compartment into said wider compartment, theother said impelling means serving to move brine over said evaporator,and means located within said tank offset for driving said shaft.

6. A refrigerating system comprising a brine tank, a partition in saidtank to control the direction of flow therethrough and having an offset,a shell-and-tube evaporator provided with a hood member, a hood memberin said partition offset, said hoods being axially aligned and spacedapart, individual impellers in said hoods, and means for driving saidimpellers.

'7. A refrigerating system comprising a tank for a heat-exchange fluid,a partition in said tank to control the direction of flow therethroughand having an offset provided with a hood member surrounding anaperture, a shell-and-tube evaporator provided with a hood member at oneend, individual impellers in said hood members, and means for drivingsaid impellers, said hoods being spaced apart so that the impeller insaid partition oilset may establish a circulation of fluid in said tankaround said partition and back to said partition oifset impeller, andthe impeller in the evaporator hood member may force a portion only ofthe circulating fluid through said evaporator, the remaining fluidbypassing the evaporator.

8. In a refrigeration system operating with a circulating heat-exchangemedium, a heatyielding element, first impeller means forestablishing acirculation of the medium over said heatyielding element under asubstantially constant head of pressure, an evaporator comprising acylindrical shell mounted with a horizontal axis and having heads,substantially horizontal tubes secured in said heads and located in thelower portion of said shell, means for supplying liquid refrigerant intosaid shell whereby it may establish a level therein above said tubes,said shell providing an accumulator space above the liquid level for theseparation of gaseous from liquid refrigerant, an outlet for gaseousrefrigerant from said accumulator space, second impeller means forestablishing a flow of a portion of said circulating heat-exchangemedium through said tubes, and a by-pass for the remaining part of thecirculating medium around said evaporator, whereby an. energetic coolingof the portion of said medium passing through the tubes is produced andthe gases of vaporization in said evaporator are permitted to separatefrom refrigerant liquid within said accumulator space.

9. In a refrigeration system operating with a circulating heat-exchangemedium, a heat-yielding element, first impeller means for establishing acirculation of the medium over said heat-yielding element under asubstantially constant head of pressure, an evaporator comprising acylindrical shell mounted with a horizontal axis and having heads,substantially horizontal tubes se- 7 second impeller means forestablishing a flow of a portion of said circulating heat-exchangemedium through said tubes, and a by-pass for the remaining part of thecirculating medium around said evaporator, whereby an energetic coolingof the portion of said medium passing through the tubes is produced andthe gases of vaporization in said evaporator are permitted to separatefrom refrigerant liquid within said accumulator space.

NORMAN H. GAY.

